Hydraulic snubbers are often used as shock absorbing devices in physical support systems that are designed to allow movement of the supported object. Such hydraulic snubbers typically include an internal control valve for controlling the shock absorbing characteristics of the snubber. In order to test the functional status of the snubber and the control valve without physically actuating the main cylinder of the snubber, hydraulic test systems have been developed for attachment to the hydraulic circuit of the snubber. Typically, the test system generates a flow of hydraulic fluid through the internal control valve of the snubber that simulates the hydraulic flow caused by actuating the main cylinder of the snubber. This procedure eliminates the need for removal and reinstallation of a snubber when checking its operational readiness.
However, conventional valves and fittings are generally not entirely suitable for attaching the portable test system to the hydraulic circuit of a snubber. Most conventional valves have an internal configuration that retains a volume of air in the closed position. If such valves were used to connect the test system to the snubber hydraulic circuit, the volume of air could be injected into the snubber hydraulic circuit. To avoid the injection of air into the hydraulic circuit, such conventional valves must be prefilled with hydraulic fluid before they are used to interconnect the test system and the snubber hydraulic circuit or before they are capped off after completion of testing. However, most conventional valves cannot be prefilled in an inverted position. Therefore, the usefulness of such conventional valves is limited. Also, at times, conventional valves used to connect two hydraulic systems together may develop leakage problems caused by improper reseating and resealing of the valve after opening and closing.
Thus, a need has arisen for a valve having a minimal air volume internal configuration that precludes the necessity for prefilling the valve with fluid before interconnecting two hydraulic systems and before installing a valve cap. Such valves could be used in an inverted position where prefilling would be difficult. Also, a need has arisen for a valve having a controlled reseating operation to avoid the possibility of leakage caused by improper reseating.